Safe and arm (S&A) systems typically provide for an interruptible explosive train between a pyrotechnic input and a pyrotechnic output in the safe condition and a contiguous explosive train located between the pyrotechnic input and the pyrotechnic output in the armed condition. A well accepted design which implements the above functionality includes a transfer charge assembly, such as a rotor or a slider, incorporating the pyrotechnic transfer charge. In the safe state of the S&A system, the transfer charge assembly inert structure constitutes a barrier between the input charge and the output charge, thereby interrupting the propagation of any pyrotechnical reaction from the input charge (if activated) to the output charge. In the arming process, the S&A system switches from safe state to armed state by movement of the transfer charge assembly. In the armed state, the transfer charge provides a pyrotechnic path from the input charge to the output charge. Specifically, the transfer charge serves as an acceptor for the pyrotechnic stimulus of the input charge, the reaction propagates through the transfer charge and the transfer charge further serves as a donor of the pyrotechnic stimulus to the output charge.
The transfer charge may consist of primary explosive or secondary explosive. A multitude of compositions for transfer charges and a multitude of corresponding manufacturing methods implemented therefor are known in the art, for example in U.S. Pat. Nos. 7,069,861, 7,052,562 and 7,040,234. Such methods include, but may be not limited to direct pressing or casting into the appropriate cavity and pre-forming the explosive pellet and mounting it into the cavity.
Micro-electromechanical systems (MEMS) are typically fabricated by employing the photo-lithography mask and etch techniques familiar to those in the semiconductor fabrication technology to form micro-miniature parts of silicon or other materials. An issue raised in U.S. Pat. No. 7,052,562, is that manufacturing of pyrotechnic charges for miniaturized S&A devices (such as MEMS-type systems) presents a special challenge, due to the small dimensions involved and the small quantity of materials involved. The filling of high explosives into very small cavities may be performed by wipe loading, pressure loading and syringe loading. A volatile mobile phase may be added to the slurry so as to partially dissolve the energetic material so that, upon evaporation of the mobile phase, the energetic material precipitates and adheres to the cavity to be filled with the explosive. The present invention provides a different method for providing explosive components, and in particular explosive train components for S&A devices.